China National Standard GB/T1804

China National Standard GB/T1804

General tolerances Tolerances for linear and angular dimensions without individual tolerance indications

GB/T1804 is equivalent to the international standard ISO 2768-1: 1989 “General tolerances – Part 1: Tolerance of linear and angular dimensions without tolerances” in the tolerance part of the linear dimension of the tolerance.

GB/T1804 specifies the general tolerance grade and limit deviation for linear dimensions.

This standard applies to the size of metal cutting, but also to the size of general stamping.

The dimensions of non-metallic materials and other processing methods can be referred to.

Normative reference

GB/T 1804-92 “General tolerances  Unfilled tolerances for linear dimensions

GB6403.4-86 “Parts rounding and chamfering

General tolerances are tolerances that are guaranteed under the general processing conditions of the workshop.

The general tolerances for linear dimensions specify four tolerance grades.

The limit value of linear dimension is shown in Table 1;

The limit deviation values of the rounding radius and the chamfer height dimension are shown in Table 2.

To specify the unfilled tolerance of the linear dimension on the drawing, the general machining accuracy of the workshop shall be considered, and the tolerance grade specified in this standard shall be selected and specified by the corresponding technical documents or standards.

Table 1. The limit value of linear dimension

Tolerance grade

Permissible deviations in mm for ranges in linear dimension

>0.5~3 >3~6 >6~30 >30~ 120 >120~ 400 >400~ 1000 >1000~2000 >2000~4000
f (fine)

±0.05

±0.05 ±0.1 ±0.15 ±0.2 ±0.3 ±0.5

m (medium)

±0.1

±0.1 ±0.2 ±0.3 ±0.5 ±0.8 ±1.2

±2

c (coarse)

±0.2

±0.3 ±0.5 ±0.8 ±1.2 ±2 ±3

±4

v (very coarse)

±0.5 ±1 ±1.5 ±2.5 ±4 ±6

±8

Table 2. The limit deviation values of the rounding radius and the chamfer height dimension

Tolerance grade

Permissible deviations in mm for ranges in the rounding radius and the chamfer height dimension

0.5~3

>3~6 >6~30

>30

f (fine)

±0.2

±0.5 ±1

±2

m(medium)
c(coarse)

±0.4

±1 ±2

±4

v(very coarse)

Representation of general tolerances for linear dimensions

Use the general tolerances specified in GB/T1804, and use the China national standard number and tolerance grade symbol on the drawings, technical documents or standards.

For example, when the medium grade is selected, it is indicated as: GB/T1804-m

The same reason, GB/T1804-f is for fine grade,  GB/T1804-c is for coarse grade and GB/T1804-v is for very coarse grade.


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